Skyworks Solutions Inc. SI5338C-B12241-GM

Overview

SI5338C-B12241-GM from Skyworks Solutions is an I²C-programmable quad clock generator with four independently configurable differential or single-ended outputs, 0.7 ps RMS typical phase jitter, PCIe Gen 1–4 Common Clock and Gen 3 SRNS compliance, and operation from 1.8/2.5/3.3 V core supply in a 4 × 4 mm 24-QFN package. It replaces up to four crystal oscillators in Ethernet switch/router and FPGA clocking systems.

For engineers reviewing the SI5338C-B12241-GM datasheet, SI5338C-B12241-GM pinout, SI5338C-B12241-GM application, or SI5338C-B12241-GM equivalent, key selection considerations include its MultiSynth™-based any-frequency synthesis (0.16–710 MHz per output), independent output voltage per driver (1.5/1.8/2.5/3.3 V), spread-spectrum capability (0.5–5.0% down-spread), and loss-of-lock/loss-of-signal alarm support.

Technical Context

The SI5338C-B12241-GM implements a two-stage PLL architecture: a high-stability reference stage (with programmable R-divider) feeding a fractional-N MultiSynth™ VCO stage (N-divider), followed by independent P-divider output paths. Each of the four output drivers supports LVPECL/LVDS/HCSL/CMOS/SSTL/HSTL formats with per-driver supply voltage selection.

It accepts flexible input references - 8–30 MHz crystal, 5–200 MHz CMOS, 5–350 MHz SSTL/HSTL, or 5–710 MHz differential - and enables glitchless frequency adjustment in 1 ppm steps and phase tuning in <20 ps increments. External feedback mode supports zero-delay operation.

Key Specifications

Pinout & Package

SI5338C-B12241-GM is housed in a 24-lead QFN package (4 × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin assignments are fixed across Si5338 family variants per Skyworks documentation (Rev. 1.6, p. 37).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad clock generator applications.

Compared with Si5332A-D08989-GM and ICS8430I-01T, the SI5338C-B12241-GM uniquely balances programmability, industrial temperature range, PCIe Gen 4 readiness, and 4-output flexibility in a compact QFN-making it optimal for mid-tier networking and embedded compute platforms where reconfigurability and BOM reduction are critical.

Availability

SI5338C-B12241-GM is available at Aetrix Electronics and suitable for Ethernet switch/router timing, PCIe Gen 3/4 clocking, broadcast video/audio sync, and FPGA & processor clocking requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for SI5338C-B12241-GM includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Skyworks Solutions is a global leader in analog and mixed-signal semiconductors, specializing in RF, mobile, infrastructure, and timing solutions with over 40 years of RF and precision timing expertise.

The Si5338 product line was designed specifically for high-performance, software-defined clock generation in networking, computing, and broadcast equipment-emphasizing jitter performance, multi-format output flexibility, and field-programmability via I²C.

FAQ

What is the maximum output frequency supported by SI5338C-B12241-GM in LVPECL format?

The SI5338C-B12241-GM supports LVPECL output frequencies up to 710 MHz, as confirmed in Table 6 of the Skyworks datasheet (Rev. 1.6, p. 8). This applies when using the MultiSynth™ VCO in integer mode and observing the Fvco/4 and Fvco/6 constraints for frequencies above 350 MHz. The device maintains 0.7 ps RMS jitter at 125 MHz and meets PCIe Gen 4 jitter specs across its full LVPECL range.

Does SI5338C-B12241-GM support spread-spectrum clocking (SSC), and what are its configuration limits?

Yes, SI5338C-B12241-GM supports per-output spread-spectrum clocking with programmable parameters: spread magnitude from 0.5% to 5.0% down-spread, modulation rate from 33 kHz to 63 kHz, and applicable to any MultiSynth™ output frequency from 5 MHz to ~Fvco/8. Default settings are 0.5% down-spread at ~31.5 kHz. Configuration is performed via I²C registers or ClockBuilder Pro software.

Can SI5338C-B12241-GM operate in clock buffer (PLL bypass) mode, and what is its additive jitter in that mode?

Yes, SI5338C-B12241-GM supports clock buffer mode with PLL bypass. In this mode, additive phase jitter is 0.165 ps RMS (12 kHz–20 MHz) and 0.225 ps RMS (50 kHz–80 MHz) for a 622.08 MHz differential input, as specified in Table 13. This mode preserves input clock integrity while providing fanout and level translation-ideal for low-jitter signal distribution without synthesis.

What input reference types does SI5338C-B12241-GM accept, and what are their respective frequency ranges?

SI5338C-B12241-GM accepts four input reference types: external crystal (8–30 MHz), CMOS single-ended (5–200 MHz), SSTL/HSTL single-ended (5–350 MHz), and differential (5–710 MHz). All inputs support loss-of-signal detection. Crystal support includes on-chip load capacitance tuning (11–13 pF) and drive-level limiting (≤100 µW) per Tables 8–11.

How is phase alignment controlled across the four outputs of SI5338C-B12241-GM?

SI5338C-B12241-GM provides independent programmable phase offset per output channel, with ±45 ns range and <20 ps step resolution (Table 5). Phase can be adjusted dynamically via I²C or dedicated PINC/FINC pins. Output-to-output skew is ≤100 ps under matched conditions (e.g., same R-divider, integer mode), enabling precise inter-channel timing alignment for multi-lane SerDes or video pixel clocking.